[R] colour code areas of a plot

[Olivier Crouzet]

On Tue, 22 Oct 2013 16:43:18 +0200
Martin Batholdy <batholdy at googlemail.com> wrote:

Hi,

you should replace your "color names" by calls to the rgb() function in
order to generate the adequate colors, something like:

bg_colors <- c(rep (rgb (0,1,0),20), rep (rgb (0,1,1),10), rep (rgb
(0,1,0),20), rep(rgb (1,0,0),5), rep(rgb (1,1,0),45)) 

(though it should obviously be automatically extracted from your data I
suppose).

Then it is possible to use the color vector as an option to
any plotting command e.g.:

plot(color_scheme$t, color_scheme$t,col=bg_colors)

or (something like):

rect(xleft = color_scheme$t[1:99], ybottom = -1, xright = color_scheme$t
[2:100], ytop = 1, col=bg_colors, lwd=0) 

Olivier.


> Hi,
> 
> I would like to colour different areas of a plot.
> But I don't know how to do this efficiently.
> 
> As an example;
> 
> lets say three stimuli were presented in an experiment, alternating,
> one at a time. Now I want to plot time on the x-axis and the
> plot-area should colour code the stimulus that was presented at that
> time interval (green for stimulus 1, yellow for stimulus 2 etc.)
> 
> 
> here an example:
> (t = time)
> 
> 
> t <- 1:100
> bg_colors <- c(rep('green',20), rep('yellow',10), rep('green',20), rep
> ('red',5), rep('yellow',45)) 
> 
> color_scheme <- data.frame(t, bg_colors)
> 
> plot(c(), c(), xlim = c(1,100), ylim=c(-1,1))
> 
> 
> rect(xleft = 1, ybottom = -1, xright = 20, ytop = 1, col = 'green',
> lwd=0) rect(xleft = 20, ybottom = -1, xright = 30, ytop = 1, col =
> 'yellow', lwd=0) …
> 
> 
> now how can I do this efficiently based on the color_scheme
> data-frame and without having to manually draw all the rectangles as
> in the example above?
> 
> 
> 
> thanks for any suggestions!
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-- 
  Olivier Crouzet, PhD
  Laboratoire de Linguistique -- EA3827
  Université de Nantes
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  France

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